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Xanthogranulomatous pyelonephritis (XGP) is an extremely rare, chronic granulomatous inflammatory condition thought to arise secondary to a combination of obstruction, recurrent bacterial infection and an incomplete immune response although the etiology of XGP is more complex. We would like to report a case of XGP occurring in a patient with polycystic kidney disease (PCKD), which has not been previously documented in etiology. A 29-year-old woman presented to our hospital with right upper quadrant pain for 5 days. She had experienced a low-grade fever, generalized weakness, and myalgia throughout her body for 2 weeks. She had no history of renal stones or recurrent UTIs. Contrast-enhanced CT revealed a well-enhancing large septated cystic mass in the right kidney and numerous cysts in the liver and both kidneys. Open right radical nephrectomy was performed due to the suspicion of renal cell carcinoma, as there was no response to antibiotics over 7 days. Gross specimen demonstrated architectural distortion due to xanthomatous nodules and a dilated pelvico-calyceal system filled with pus and blood. Microscopic examination revealed infiltration of neutrophils and lipid-laden macrophages. The patient is currently being followed up in the outpatient clinic without recurrence of XGP. This is the first reported case of XGP in a patient with underlying PCKD. Physicians should consider PCKD as a potential underlying cause of XGP.

Key Clinical Message In the context of lymphoma, it is of paramount importance to perform subsequent Positron Emission Tomography‐Computed Tomography (PET‐CT) scans to ensure the comprehensive eradication of neoplasms. Abstract Primary renal diffuse tumors constitute less than 1% of all renal neoplasms. Among these, diffuse renal large B‐cell lymphoma is an exceedingly rare extranodal lymphoma. A 64‐year‐old male presented to the Department of Urology with complaints of persistent left flank discomfort for a duration of 2 weeks. Additionally, he reported generalized weakness, fatigue, and symptoms indicative of lower urinary tract obstruction, such as discomfort in the left testicle and dysuria. Ultrasound imaging revealed an echogenic structure with thickened, reactive walls and a turbid fluid core, located in the left flank, proximal to the lower pole of the kidney. This structure was subsequently identified as diffuse renal large B‐cell lymphoma. For the diagnosis of large B‐cell lymphomas, it is imperative that a proficient hematopathologist performs a comprehensive examination of the tumor tissue, preferably utilizing an excisional biopsy. The categorization of lymphoma requires specialized tests such as immunohistochemistry, flow cytometry, fluorescence in situ hybridization (FISH), and molecular testing. In instances where a renal mass is detected, healthcare professionals should consider performing a biopsy. In lymphoma cases, follow‐up Positron Emission Tomography‐Computed Tomography (PET‐CT) scans are crucial to confirm the complete eradication of the tumor.

Tuberous sclerosis complex (TSC) is a genetically inherited disorder distinguished by the development of numerous benign neoplasms across multiple organ systems.Renal angiomyolipoma represents 0.3% of all primary renal tumors and are classified as benign mixed mesenchymal neoplasms. In this report, we reported the clinical presentation of a 28-year-old individual who was received by the department of urology. The patient was admitted presenting with asymptomatic, macroscopic hematuria that had been ongoing for a period of 10 days. Subsequent diagnostic evaluations revealed an association between the presenting urinary condition and tuberous sclerosis complex with a concurrent renal angiomyolipom

Mixed epithelial and stromal tumor of the kidney (MESTK) is a rare benign kidney tumor. In rare cases, malignant transformation, such as sarcomatoid features indicates poor clinical outcomes.In this study, we will describe a 45 years old man with a diagnosis of MESTK with malignant transformation of the sarcomatoid component, after right radical nephrectomy. The patient underwent chemotherapy with adriamycin, ifosfamide, and granulocyte-colony stimulating factor (G-CSF).The radiological characteristics of MESTK can pose diagnostic challenges due to its non-unique radiological appearance. The presence of sarcomatoid transformation is a hallmark feature of malignant MESTK which can be very aggressive.

The extent of renal biopsy indication is being widened because of the increasing incidence of incidental renal masses; the increasing treatment options for renal cell carcinoma, including ablation therapy and novel targeted treatment; and the increasing incidence of kidney transplantation. However, percutaneous renal biopsy is technically difficult, particularly for beginners, because the skin-to-organ distance is relatively longer than those associated with other organs. In the present review, we will discuss the indications, technical considerations, efficacy, and complications of renal biopsy. Furthermore, we share practical tips of renal biopsy through many examples to help radiologists perform renal biopsy safely and effectively in various situations.

Abstract Background The purpose of this study was to compare the surgical, functional, and oncological outcomes between open partial nephrectomy (OPN) and laparoscopic partial nephrectomy (LPN). Methods This prospective, randomized study was performed on patients who underwent partial nephrectomy under general anesthesia. Patients were randomized using the closed envelope method to either LPN or OPN. Baseline demographics and surgical, functional, and oncological outcomes were compared. A per-protocol analysis was used. Results Randomized study was conducted on 166 patients. The LPN, in comparison to the OPN group, was associated with significantly shorter hospital stay (3 vs. 4 days), less blood transfusion (10% vs. 12%), longer operative time (134 min vs. 124 min), lower visual analog pain score (7 vs. 8), and lower estimated GFR (70.7 ± 17.5 vs. 72.3 ± 14.7). Conclusions Oncological and functional results were comparable between LPN and OPN. However, LPN was superior to open surgery because of less hospital stay, visual analog pain score, and blood loss.

Abstract Background Small renal mass (SRM) biopsy remains under-utilized due to stigma. Meanwhile, the alarmingly high benign findings in resected kidney masses highlight the need for improved preoperative diagnosis and patient selection. Methods The purpose of this study is to review the success rate of SRM biopsy and to evaluate its impact on patient management. A total of 168 percutaneous image-guided core needle biopsies (CNBs) of SRMs were retrieved at a tertiary academic center between 2015 and 2019. Subsequent treatment choices, side effects and outcomes were retrospectively reviewed. Results The diagnostic rate of CNB was 86.9%. Benign neoplasms accounted for a significant portion (14.3%) of SRM. Renal cell carcinomas (RCCs) were the most common diagnoses (69.6%) as expected. In biopsy-resection correlation, the positive predictive value of CNB was 100%. Tumor typing and subtyping by CNB were highly accurate, 100% and 98.3% respectively. Nuclear grading for clear cell RCC was accurate in 83.8% cases. The CNB results had significant impact on treatment. Most patients with RCCs underwent either resection (54.1%) or ablation (33.9%), in contrast to observation in benign neoplasms (90.5%). Most importantly, the benign resection rate (3.2%) in this series was much lower than the national average. Conclusion CNB provided accurate diagnoses for the majority of SRMs and revealed benign diagnoses in a subset of clinically suspicious lesions. Employment of CNB in suspicious SRM may help avoid overtreatment for benign lesions.

Matthew Chau,* Ivan Thia,* Manmeet Saluja Royal Perth Hospital, Perth, Western Australia, Australia*These authors contributed equally to this workCorrespondence: Matthew Chau, Department of Urology, Level 11. Royal Perth Hospital, Victoria Square, Perth, Western Australia, 6000, Australia, Tel +61 8 9224 2244, Email matthew.chau@health.wa.gov.auObjectives: The role of needle core renal biopsy in large renal masses, defined as lesions larger than 4 cm, is debatable, as larger renal masses are associated with malignant histology. We aim to review the safety and impact of renal biopsy on the management of large renal masses.Methods: A retrospective, single-center review of all renal biopsies performed between January 2011 and December 2020 at Royal Perth Hospital was conducted. Indications for biopsy, complications and final management plans were correlated to assess the value of biopsies in large renal masses.Results: In total, 126 biopsies were performed. Indeterminate imaging findings and comorbidities were the main indications for biopsies. We identified 116 (92.1%) diagnostic biopsies and 10 (8.0%) non-diagnostic biopsies due to insufficient samples or inflammatory tissue. Of the diagnostic biopsies, 99 (78.6%) were malignant and 17 (13.5%) were benign. Unnecessary extirpative surgery was avoided in 17 patients. Histology included renal cell carcinoma (96%) and other malignancies such as urothelial carcinoma (3%) and non-Hodgkin’s lymphoma (1%). Benign biopsies identified histology including angiomyolipoma (35.3%) and oncocytoma (52.5%). The median follow-up time was 68 months (range 19– 132 months).Conclusion: Renal biopsies in large renal masses may aid in preventing unnecessary surgery, especially in situations where imaging findings are equivocal or in patients with many comorbidities.Keywords: biopsy, kidney neoplasms, nephrectomy, renal mass

Background: There is a lack of evidence on acute kidney injury (AKI) and new-onset chronic kidney disease (CKD) after surgery for localised renal masses (LRMs) in patients with two kidneys and preserved baseline renal function. Objective: To evaluate the prevalence and risk of AKI and new-onset clinically significant CKD (csCKD) in patients with a single renal mass and preserved renal function after being treated with partial (PN) or radical (RN) nephrectomy. Design, setting, and participants: We queried our prospectively maintained databases to identify patients with a preoperative estimated glomerular filtration rate (eGFR) of ≥60 ml/min/1.73 m2 and a normal contralateral kidney who underwent PN or RN for a single LRM (cT1-T2N0M0) between January 2015 and December 2021 at four high-volume academic institutions. Intervention: PN or RN. Outcome measurements and statistical analysis: The outcomes of this study were AKI at hospital discharge and the risk of new-onset csCKD, defined as eGFR

It is extremely rare for granulomatosis with polyangiitis to form masses in the kidneys. Magnetic resonance imaging findings of renal masses caused by this disease have been infrequently reported. In this study, we report a case of renal masses caused by granulomatosis with polyangiitis with different findings. While on steroid treatment for a recently diagnosed granulomatosis with polyangiitis, a man in his 60s underwent computed tomography for a hepatic dysfunction. Computed tomography showed incidental findings of a 40 mm × 35 mm mass in the left kidney and two 8 mm × 8 mm masses in the right kidney; all masses were hypovascular. On magnetic resonance imaging, the left renal mass showed a hyperintense signal with slightly hypointense signal rim on T2-weighted imaging. The left renal mass showed a strong hypointense signal where the mass abutted the renal capsule. On diffusion-weighted imaging, the left renal mass showed an isointense signal with a hyperintense signal rim. Both right renal masses showed an isointense signal with slightly hypointense signal rim on T2-weighted imaging and hyperintense signal on diffusion-weighted imaging. Suspecting renal masses caused by the disease, the patient was then treated with steroids and methotrexate. After 6 months of treatment, both right renal masses resolved; however, the left renal mass shrank but abnormal signal remained. Based on the treatment course, it is conceivable that the renal masses were caused by granulomatosis with polyangiitis.

Introduction: Active surveillance has become a standard of care for the management of small renal masses. Decision to transition from surveillance to intervention relies on several factors including growth kinetics, histologic grade on biopsy and patient comorbidities. Management of renal masses in pregnancy presents a unique change when clinical triggers must be weighed with risk to fetus. We present the case of a third trimester patient with an enlarging and enhancing renal mass managed with robotic assisted laparoscopic partial nephrectomy. Histologic analysis was consistent with renal leiomyoma. Renal leiomyomas are a rare benign mesenchymal tumor influenced by changes in progesterone-estrogen axis.

Small renal masses (SRM) are defined as contrast-enhancing solid masses detected on diagnostic imaging, with a size of less than or equal to 4cm, corresponding to renal cell carcinoma stage T1a. These tumours are mainly benign, with an indolent nature and rare metastatic potential. Given the size and nature of these tumours, there has been a significant evolution and in management modalities of these tumours. These range from conventional radical approaches such as radical nephrectomy, partial nephrectomy, to more conservative approaches such as active surveillance, and some novel emerging management strategies such as various thermal ablation techniques. The treatment decision depends on patient factors such as age and co-morbidity, and tumour factor on radiological imaging, such as tumour size, location, growth rate and biopsy result. In this review, we aim to provide the latest updates on approaching SRM and various management modalities.

Purpose: The purpose of the study is to assess the value of RENAL nephrometry score (RNS) in predicting surgical decisions, complications, and decreases in kidney function in patients with localized renal tumors. Methods: Cases with solitary, solid, and enhancing renal masses were included, scheduled for nephron-sparing surgery (NSS), and assessed using routine laboratory and radiological data necessary for calculating the RENAL score. The primary endpoint was conversion to radical nephrectomy (RN), while the secondary endpoint was the prediction of a drop in renal function assessed by postoperative estimated glomerular filtration rate (eGFR) at the last follow-up visit compared with the preoperative values. The association between the scoring system and perioperative outcomes was evaluated. Results: In all, 84 cases were included, NSS was accomplished in 67 cases while conversion to RN was mandatory in 17 patients, median (interquartile range) RENAL score was 6.2 (4–10) for NSS and 9.7 (6–12) for RN (P < 0.001). Higher grades of complications were observed in the high-complexity subgroup. eGFR was 79.8 that dropped to 75.6 ml/min/1.73 m2 in the late value in patients who underwent NSS, while it was 82.9 that dropped to 58.3 ml/min/1.73 m2 in the late value in patients who converted into RN (P < 0.001). The percentage of drop in eGFR was significantly higher in the moderate and high-risk groups, which was positively correlated with the warm ischemia time. Regression analysis revealed that the continuous RENAL score was a more significant predictor of conversion to RN than tumor size alone. In the 67 NNS cases, the percentage decrease in eGFR was predicted using the continuous RENAL score. Conclusion: The RNS is a significant predictor of conversion to RN and can predict the percentage decrease in eGFR after NSS. Further investigations and follow-ups are necessary.

Abstract Background Ewing’s sarcoma is categorized as small round cell aggressive tumor which commonly occurs in bone and soft tissue. Primary renal Ewing’s sarcoma is an extremely rare entity and accounts for less than 1% of renal masses. It is characterized by a very aggressive course, with very few reported cases in the literature. Primary renal Ewing’s sarcoma is indistinguishable from renal cell carcinoma on anatomical imaging and therefore need histopathological correlation for confirmation. The positron emission tomography (PET) fused with computed tomography (CT) helps in the evaluation of disease, for staging and metastatic workup. Case presentation We present a case of 48-year-old lady who presented to urology department with difficulty in passing urine for 5 months associated with pain in the right flank region. She had an episode of haematuria 5 months back. Contrast enhanced CT showed a large lobulated heterogeneously enhancing right retroperitoneal mass in renal fossa. Histopathological examination and immunohistochemistry were suggestive of Ewing’s sarcoma. The PET/CT revealed FDG avid right renal mass with lymph nodal and skeletal metastasis. Conclusions Ewing’s sarcoma being aggressive tumour usually present with bone, liver and lung metastasis along with lymph nodal metastasis at time of diagnosis. The 18 F FDG PET/CT helps in diagnosis, staging, appropriate treatment planning, restaging, response evaluation and prognostication of Ewing’s sarcoma.

Renal cryoablation (CA) has become an accepted treatment option for patients with small renal tumors and co-morbidities that make them less favorable for surgical intervention. Complications from renal CA have been previously reported and are generally associated with increasing size and central location of the tumor. Ureteral injury from renal CA, although rare, can be difficult to manage and may require complex surgeries in patients who are poor surgical candidates to begin with. We report a case of a renal mass CA complicated by proximal ureteral necrosis and transection, treated with multiple minimally invasive procedures ultimately resulting in successful bridging of the necrotic segment with nephroureteral stent and thus avoiding major surgery.

Wilms tumor is rare in adults, constituting only 0.5% of all renal masses. Tumors in adults are diagnosed later than those in children, and survival after treatment is still low. Some reasons for this are considered as patients not receiving neoadjuvant chemotherapy before surgery and late initiation of treatment due to delays in receiving pathology results. In this paper, we present a 38-year-old male patient diagnosed with Wilms tumor after percutaneous biopsy and review the related literature.

PurposeTo automatically evaluate renal masses in CT images by using a cascade 3D U-Net- and ResNet-based method to accurately segment and classify focal renal lesions.Material and MethodsWe used an institutional dataset comprising 610 CT image series from 490 patients from August 2009 to August 2021 to train and evaluate the proposed method. We first determined the boundaries of the kidneys on the CT images utilizing a 3D U-Net-based method to be used as a region of interest to search for renal mass. An ensemble learning model based on 3D U-Net was then used to detect and segment the masses, followed by a ResNet algorithm for classification. Our algorithm was evaluated with an external validation dataset and kidney tumor segmentation (KiTS21) challenge dataset.ResultsThe algorithm achieved a Dice similarity coefficient (DSC) of 0.99 for bilateral kidney boundary segmentation in the test set. The average DSC for renal mass delineation using the 3D U-Net was 0.75 and 0.83. Our method detected renal masses with recalls of 84.54% and 75.90%. The classification accuracy in the test set was 86.05% for masses (

Abstract Background Metanephric adenoma (MA) is a rare benign renal tumor that resembles renal cell carcinoma and Wilms’ tumor in radiological as well as pathological appearance. It can present at any age or gender, and it is extremely rare in the pediatric age group with less than 50 reported cases. Fanconi–Bickel syndrome (FBS) is a rare autosomal recessive disorder of carbohydrate metabolism. Herein, we report a rare incidence of MA in a boy with a genetically confirmed FBS who underwent a nephron-sparing surgery. Case presentation A 21-month-old boy was referred to the pediatric urology clinic for further evaluation of an incidentally discovered left renal mass. His laboratory investigations showed normal renal function, hypophosphatemia, high blood glucose level, markedly elevated serum alkaline phosphatase, and low serum vitamin D. Blood picture showed signs of polycythemia and urinalysis showed glucosuria and aminoaciduria. Genetic testing was positive for Fanconi–Bickel syndrome. Radiological investigations were carried out with abdominal ultrasound and computerized tomography (CT) with intravenous contrast documented a sharply marginated peripheral hypoechoic hypovascular homogeneously enhancing mass at the upper pole of the left kidney measuring 2.0 × 1.8 × 2.0 cm. The child was admitted and started on supportive treatment until his medical condition was stabilized, then underwent elective open left partial nephrectomy via a left upper transverse abdominal transperitoneal incision. The excised renal mass was sent for histopathological assessment and was found to be a tumor composed of tightly packed tubules with no mitotic figures or necrosis and scanty cytoplasm consistent with MA. After good hydration and tumor resection, his polycythemia gradually improved. The patient was discharged home in a good condition with his proper replacement therapies. His follow-up abdominal ultrasound after 12 months showed no signs of recurrence. Conclusions Metanephric adenoma is extremely rare in the pediatric age group, especially in those who have a FBS. The only way to diagnose and treat this tumor is by surgical resection as most patients are asymptomatic. A nephron-sparing surgery is better for this age group in which the future renal function is considered.

The efficacy and complication rates of percutaneous radiofrequency ablation (RFA) and cryoablation (CA) in the treatment of T1 renal masses in two Northern Italy hospitals were retrospectively investigated. Eighty-two patients with 80 T1a tumors and 10 T1b tumors treated with thermal ablation from 2015 through 2020 were included. A total of 43 tumors in 38 patients were treated with RFA (2.3 ± 0.9 cm), and 47 tumors in 44 patients were treated with CA (2.1 ± 0.8 cm). The mean follow-up observation period was 26 ± 19 months. The major complications and efficacy, as measured using the technical success and local tumor recurrence rates, were recorded. There were three (6.9%) technical failures with RFA and one (2.1%) with cryoablation (p = 0.30). Among the 40 tumors that were successfully treated with RFA, 1 tumor (2.5%) developed local tumor recurrence; 5/46 tumors that were treated with cryoablation (10.8%) developed local tumor recurrence (p = 0.17). T1b lesions (4.0 ± 0.7 cm) resulted in 1/6 technically unsuccessful cases with RFA and 0/4 with CA. No recurrent disease was detected in the T1b lesions. Major complications occurred after 2.3% (1/43) of RFAs and 0/47 of cryoablation procedures. RFA and cryoablation are both effective in the treatment of renal masses. Major complications with either procedure are uncommon.

The incidence of renal mass detection has increased during recent decades, with an increased diagnosis of small renal masses, and a final benign diagnosis in some cases. To avoid unnecessary surgeries, there is an increasing interest in using radiomics tools to predict histological results, using radiological features. We performed a narrative review to evaluate the use of radiomics in renal mass characterization. Conventional images, such as computed tomography (CT) and magnetic resonance (MR), are the most common diagnostic tools in renal mass characterization. Distinguishing between benign and malignant tumors in small renal masses can be challenging using conventional methods. To improve subjective evaluation, the interest in using radiomics to obtain quantitative parameters from medical images has increased. Several studies have assessed this novel tool for renal mass characterization, comparing its ability to distinguish benign to malign tumors, the results in differentiating renal cell carcinoma subtypes, or the correlation with prognostic features, with other methods. In several studies, radiomic tools have shown a good accuracy in characterizing renal mass lesions. However, due to the heterogeneity in the radiomic model building, prospective and external validated studies are needed.

Primary renal primitive neuroectodermal tumors (PNET) are an extremely rare entity. The tumor is very aggressive presenting with metastasis and carries a dismal prognosis. We describe the case of renal PNET in an 11-year-old boy with a solid cystic lesion in the right kidney with a thrombus in the inferior vena cava and lung nodules, mimicking Wilms' tumor.

This study aimed to retrospectively analyze the features of contrast-enhanced ultrasound (CEUS) of renal masses that cannot be detected by conventional ultrasound (CUS). The data of 264 patients who underwent CEUS for renal lesions from January 2016 to December 2019 were retrieved. Of these, 16 patients with renal masses which were not detected by CUS were included in the final analysis. The corresponding characteristics of CEUS were evaluated, including intensity of enhancement, homogeneity, wash-in and wash-out patterns, and perilesional rim-like enhancement. Of the 16 patients, 10 patients had clear cell renal cell carcinoma (ccRCC) and 6 patients had urothelial carcinoma of the renal pelvis (UCRP). Compared with the location on non-enhanced computed tomography (CT) scan, all tumors were detected on CEUS. Most (7/10) of the ccRCCs appeared as hyperenhancement, homogeneous enhancement, synchronous-in, and no perilesional rim-like enhancement. Most (4/6) of the UCRPs appeared as isoenhancement, slow-in, fast-out, and no perilesional rim-like enhancement. CEUS may be helpful in the diagnosis and differential diagnosis of renal tumors which were not observed on CUS, and it might be an alternative method for some patients when contrast-enhanced computed tomography (CECT) or magnetic resonance imaging (MRI) cannot be performed.

Spinal cord involvement of Wilms' tumour is rare. A 14-year-old girl presented with an abdominal mass, paraplegia and loss of bladder and bowel control. Radiological investigations confirmed the presence of a large intraabdominal mass with infiltration into the spinal canal with impingement of nerve roots and the spinal cord. Histopathological evaluation demonstrated a nephroblastoma. It was decided to commence prompt neoadjuvant chemotherapy to render the tumour amenable to surgical resection. The patient unfortunately demised before receiving her first dose. Early diagnosis and timeous initiation of treatment is critical in limiting morbidity and mortality associated with malignant spinal cord compression.

Objective: To evaluate the contemporary role of open partial nephrectomy at a referral high-volume kidney cancer Center, presenting our step-by-step technique of open tumor enucleation. Patient and Surgical Procedure: We queried our prospectively database to select patients undergoing open PN for non-metastatic renal masses at our Center between January 2017 and December 2020. Preoperative patients’ and tumors’ characteristics were recorded. Overall, open PN was performed by a single highly experienced surgeon (S.S.) (> 500 RAPN; > 500 open PN) following established principles. In this video we present a case of a 69-year-old patient with a highly complex (PADUA 10), cT2N0M0, predominantly endophytic 8 cm renal mass in a congenital right solitary kidney (preoperative eGFR 73 ml/min/1.73 m2), with no previous abdominal surgery, undergoing open PN. Results: Overall, of 428 patients treated with PN at our Center in the study period, 422 (98.6%) underwent RAPN while 6 (1.4%) open PN. There were no intraoperative adverse events. Perioperative major (Clavien-Dindo grade > 3) complications were recorded in two patients. In the case shown in the video, the overall operative time was 240 min, while warm ischemia time 35 min. The postoperative course was uneventful, and the patient was discharged on postoperative day (POD) 6 in good clinical conditions and with an eGFR of 53.7 ml/min/1.73 m2. The patient was then readmitted on POD 13 for an active bleeding from a small renal pseudoaneurysm detected by an angio-computed tomography scan. Therefore, the patient underwent super-selective embolization, and discharged four days later in good clinical conditions and with an eGFR of 49 ml/min/1.73 m2. Histopathological examination revealed a pT3a Nx ISUP grade 3 clear cell renal cell carcinoma, with negative surgical margins. Conclusions: While robotic approach has almost replaced open PN at referral high- volume Centers worldwide for localized renal masses, carefully selected patients may still benefit from an open approach.

In the 2016 World Health Organization renal tumor classification, the mixed epithelial and stromal tumor family was introduced as a new entity. This family encompasses a spectrum of tumors, ranging from predominantly cystic tumors (adult cystic nephromas) to tumors that are variably solid (mixed epithelial and stromal tumors). The majority of previous studies incorporating “mixed epithelial and stromal tumor” in the titles were actually reports of imaging findings of adult cystic nephroma. Thus, the solid component of mixed epithelial and stromal tumors has not been well evaluated. In this study, we present 2 cases of mixed epithelial and stromal tumors, as defined by the 2016 World Health Organization classification, showing a predominantly solid component. The characteristic findings of the solid component of these tumors were T2-hypointensity on magnetic resonance imaging and hyperattenuation on unenhanced computed tomography. Angiomyolipoma with epithelial cysts and epithelioid angiomyolipoma should be considered in the differential diagnosis of mixed epithelial and stromal tumors.

Abstract Background Erdheim-Chester disease (ECD) is a rare non-Langerhans histiocytosis with slow progression over the years that is particularly difficult to diagnose. Cases Here we report three cases of ECD without BRAF mutation presenting with a renal mass, hairy kidney appearance, and a rather benign course, for which the diagnosis of ECD was delayed, characterized by multiple investigations and unsuccessful treatments attempts. In two cases the distinction from IgG4-related disease required multiple investigations and reevaluation of the clinical, radiological, histological, and immunological characteristics. Conclusion A correct diagnosis of ECD may take several years and often requires revisiting previous hypotheses. Reassessment of histological slides and more modern complementary exams such as PET-CT or BRAF and MAPK-ERK mutation analysis can help to confirm the diagnosis of ECD and to select effective therapy.

Abstract Introduction Squamous cell carcinoma of the renal pelvis is a rare neoplasm, accounting for less than 0.8% of malignant renal tumors. Chronic irritation is believed to be the primary pathogenic cause for squamous cell carcinoma of the renal pelvis. The most frequently reported cases of squamous cell carcinoma of the renal pelvis generally present with hydronephrosis, pyelonephritis, or nephrolithiasis. The skin of the flank is a very uncommon site of clinical presentation. Here, we report an exceedingly rare case of squamous cell carcinoma of the renal pelvis presenting as skin invasion of the flank. Case presentation A 66-year-old Han Chinese man consulted our hospital because of a right lumbar skin lesion lasting more than 3 months. His physical examination revealed that he had a palpable mass about 6.0 cm × 5.0 cm in size at the posterior axillary line in the right low back with skin ulceration 3 mm in diameter and exudation on it. Magnetic resonance imaging showed hydronephrosis of the right kidney and plaque-like abnormal signal in the middle portion of the kidney. The patient underwent a right nephrectomy. The sinus tract formation between the ulcerative skin in the right low back and the middle portion of the right kidney could be found. The distended kidney could not be excised entirely for tight adhesion. Pathological examination showed moderately differentiated renal squamous cell carcinoma with invasion of the renal parenchyma and perirenal adipose tissue. Conclusion It is extremely rare for renal squamous cell carcinoma to present as skin invasion. Recurrent percutaneous nephrolithotomy may be a risk factor for squamous cell carcinoma of the renal pelvis. The possibility of renal squamous cell carcinoma should be kept in mind in patients who have hydronephrosis, nephrolithiasis, or chronic pyelonephritis for a long time or with renal anomalies. More radiological examinations are suggested for such patients.

ObjectivesThis study was conducted in order to develop and validate an ultrasonic-based radiomics nomogram for diagnosing solid renal masses.MethodsSix hundred renal solid masses with benign renal lesions (n = 204) and malignant renal tumors (n = 396) were divided into a training set (n = 480) and a validation set (n = 120). Radiomics features were extracted from ultrasound (US) images preoperatively and then a radiomics score (RadScore) was calculated. By integrating the RadScore and independent clinical factors, a radiomics nomogram was constructed. The diagnostic performance of junior physician, senior physician, RadScore, and radiomics nomogram in identifying benign from malignant solid renal masses was evaluated based on the area under the receiver operating characteristic curve (ROC) in both the training and validation sets. The clinical usefulness of the nomogram was assessed using decision curve analysis (DCA).ResultsThe radiomics signature model showed satisfactory discrimination in the training set [area under the ROC (AUC), 0.887; 95% confidence interval (CI), 0.860–0.915] and the validation set (AUC, 0.874; 95% CI, 0.816–0.932). The radiomics nomogram also demonstrated good calibration and discrimination in the training set (AUC, 0.911; 95% CI, 0.886–0.936) and the validation set (AUC, 0.861; 95% CI, 0.802–0.921). In addition, the radiomics nomogram model showed higher accuracy in discriminating benign and malignant renal masses compared with the evaluations by junior physician (DeLong p = 0.004), and the model also showed significantly higher specificity than the senior and junior physicians (0.93 vs. 0.57 vs. 0.46).ConclusionsThe ultrasonic-based radiomics nomogram shows favorable predictive efficacy in differentiating solid renal masses.

A 13-year-old neutered male Maltese dog presented with a three-month history of haematuria. The abdominal ultrasound and computed tomography revealed a large, multifocally-calcified left renal mass that was disrupting most of the renal parenchyma. Most of the areas of this mass did not show any contrast enhancement on the CT. After a nephrectomy, renal telangiectasia was diagnosed on the histopathology. Renal telangiectasia is a hereditary dysplastic blood vessel disease only previously reported in Pembroke Welsh Corgi. This is the first diagnostic imaging report of renal telangiectasia and the first report in a Maltese. Renal telangiectasia should be considered for the differential diagnosis of destructive renal masses with faint or no contrast enhancement on a CT, even in cases of unilateral renal involvement in Maltese dogs or those in non-corgi breeds.

Abstract Background Almost all cases of renal hydatid cysts need surgical intervention for treatment. We report a case of isolated renal hydatid cyst treated successfully only with medical therapy. Case presentation This case is a 79-year-old veterinarian presented with right flank pain, hydatiduria and positive echinococcus granulosus serology. A 70*50 mm cyst with daughter cysts in mid-portion of right kidney on presentation was changed into a 60*40 mm cyst without daughter cysts at last follow-up. Due to patient’s refusal of surgery, our patient received medical treatment including praziquantel and albendazole. After completion of first round of treatment, recurrence occurred and the same treatment was repeated. At last, the cyst became inactive and calcified with negative serology and no clinical symptoms under medical treatment. Conclusion The treatment of choice in renal hydatid cyst is surgery; although there are some reports about the efficacy of medical treatments for hydatid cysts but lower rates of recurrence and higher efficacy put surgery in a superior position compared to medical approaches. Our case showed relative success of medical treatment, despite the presence of a large multilocular renal involvement. Thus, medical therapy without surgery can be considered in very particular cases with isolated renal hydatid cysts.

Abstract Background It was difficult to compare the outcome of partial nephrectomy among different studies due to the absence of standardized description of different renal masses. This problem led to the development of nephrometry scoring systems. R.E.N.A.L. is among the commonest nephrometry scoring systems; however, some studies failed to find any relation between R.E.N.A.L. with perioperative outcome. We evaluated our designed newly modified nephrometry score in prediction of outcome following partial nephrectomy and compared its predictability versus original R.E.N.A.L. Methods Fifty-one patients with cT1-2N0M0 renal masses amenable for partial nephrectomy were included prospectively. Different perioperative outcome variables were compared according to complexity level in R.E.N.A.L. and the newly modified nephrometry score. Results Clinical staging was T1a (21.6%), T1b (49%), T2a (25.5%), T2b (3.9%). Median R.E.N.A.L. was 9 (4–12). Hilar position and intrarenal pelvis were detected in 19.6% and 68.6%. Low, moderate and high complexity masses were found in 21.6%, 39.2% and 39.2%. Complications and rate of conversion to radical nephrectomy were 17 (33.3%) and 4 (7.8%). The only significantly affected variable (p = 0.039) by R.E.N.A.L. was rate of secondary intervention, but it was higher in low than in high complexity level. In the newly modified nephrometry score, complications (p = 0.037) and rate of positive surgical margin (p = 0.049) were significantly higher with increased complexity level. Although other variables (pelvi-calyceal system entry, operative time, blood loss, hemoglobin loss, blood transfusion and conversion to radical nephrectomy) did not show statistically significant difference according to both scores, they were better associated with the complexity level in the newly modified nephrometry score with their remarkable increase in the high when compared to the low complexity level. Conclusions The newly modified nephrometry score was associated with better prediction of outcome of partial nephrectomy when compared to R.E.N.A.L.

Automated classification of renal masses detected at computed tomography (CT) examinations into benign cyst versus solid mass is clinically valuable. This distinction may be challenging at single-phase contrast-enhanced CE-CT examinations, where cysts may simulate solid masses and where renal masses are most commonly incidentally detected. This may lead to unnecessary and costly follow-up imaging for accurate characterization. In this paper, we describe a patch-based CNN method to differentiate benign cysts from solid renal masses using single-phase CECT images. The predictions of the network for patches extracted from a manually segmented lesion are combined through the majority voting system for final diagnosis. We used a dataset comprised of single-phase CECT images of 315 patients with 77 benign (oncocytomas, and fat poor renal angiomyolipoma) and 238 malignant (renal cell carcinoma including clear cell, papillary, and chromophobe subtypes) tumors. We trained our proposed network using patches extracted and artificially augmented from 40 CECT scans. The presented algorithm was evaluated using 275 unseen CECT test images consisting of 327 renal masses by comparing algorithm-generated labels to those labeled by experts and achieved mean accuracy, precision, and recall of 88.96%, 95.64%, and 91.64%. Our method yielded accuracy of 91.21% ± 25.88% as mean ± standard deviation at the patient level. The AUC was reported as 0.804. The results indicate that our algorithm may accurately characterize benign cysts from solid masses with a high degree of accuracy and may be clinically valuable to prevent unnecessary imaging follow-up for characterization in a proportion of patients.

Angiomyolipoma (AML) is a benign renal mass that can be treated with nephron sparing surgery or transarterial embolization. Embolization has been favored due to efficacy and safety profile. This case demonstrates a previously undocumented phenomenon of AML treated with transarterial embolization using Lipiodol® (Guerbet LLC, Princeton, NJ) resulting in nephrolithiasis and retention of Lipiodol® two years after original embolization. Although Lipiodol®-based embolization has not been shown to cause nephrolithiasis, it may have been the nidus for stone formation, and this is an important potential complication worthy of further study.

Purpose: Clinicians rely on imaging features to calculate complexity of renal masses based on validated scoring systems. These scoring methods are labor-intensive and are subjected to interobserver variability. Artificial intelligence has been increasingly utilized by the medical community to solve such issues. However, developing reliable algorithms is usually time-consuming and costly. We created an international community-driven competition (KiTS19) to develop and identify the best system for automatic segmentation of kidneys and kidney tumors in contrast CT and report the results.Methods: A training and test set of CT scans that was manually annotated by trained individuals were generated from consecutive patients undergoing renal surgery for whom demographic, clinical and outcome data were available. The KiTS19 Challenge was a machine learning competition hosted on grand-challenge.org in conjunction with an international conference. Teams were given 3 months to develop their algorithm using a full-annotated training set of images and an unannotated test set was released for 2 weeks from which average Sørensen-Dice coefficient between kidney and tumor regions were calculated across all 90 test cases.Results: There were 100 valid submissions that were based on deep neural networks but there were differences in pre-processing strategies, architectural details, and training procedures. The winning team scored a 0.974 kidney Dice and a 0.851 tumor Dice resulting in 0.912 composite score. Automatic segmentation of the kidney by the participating teams performed comparably to expert manual segmentation but was less reliable when segmenting the tumor.Conclusion: Rapid advancement in automated semantic segmentation of kidney lesions is possible with relatively high accuracy when the data is released publicly, and participation is incentivized. We hope that our findings will encourage further research that would enable the potential of adopting AI into the medical field.

Schwannomas of the kidney are rare with only a handful of cases reported in literature. We present a case of a large Schwannoma of the right kidney causing mass effect with imaging characteristics thought to represent renal cell carcinoma. On imaging, these masses present similarly to solid renal masses and are therefore indistinguishable without tissue diagnosis. Thus, surgical resection is the definitive treatment for renal schwannomas.

Objective:The aim of this study was to investigate the use and types of hemostatic agents (HAs) used during partial nephrectomy (PN) and the relationship of the number of these agents used during surgery with tumor size, RENAL nephrometry score (NS), peroperative ischemia time, and postoperative pathology results.Materials and Methods:Records of patients, who had undergone PN in our clinic due to renal mass between January 2013 and February 2019, were retrospectively reviewed. Our study included 71 patients who were administered one or more HAs during PN. Demographic characteristics, operative data, and pathological results of patients, who were administered one or more HAs during PN, were recorded.Results:Cellulose-based agents and polytetrafluoroethylene pledgets were the most frequently used HAs (78.8% and 38%, respectively). The patients were divided into two groups according to tumor size (0-4 cm and larger than 4 cm tumors), RENAL NS (low and intermediate-high score), ischemia time (0-20 min and longer than 20 min), and tumor pathology result (benign and malignant tumor), and the number of HAs used in each group was compared. When the groups were compared separately in terms of number of HAs used, no statistically significant difference was found between the groups (p=0.323, p=0.183, p=0.618, and p=0.131, respectively).Conclusion:HAs are frequently used in our clinic to achieve hemostasis. There was no statistically significant difference in the number of HAs used between the groups.

Abstract Background Strong evidence comparing effectiveness between nephron-sparing intervention (NSI) and active surveillance (AS) is lacking. Thus, we aim to compare the outcomes of survival, including cancer-specific survival (CSS), overall survival (OS), and cardiovascular-specific survival (CVSS), in patients with renal masses who underwent NSI or AS. Methods A systematic literature search of PubMed, Web of Science, and EMBASE was performed for citations published prior to September 2018 that described NSI, partial nephrectomy and thermal ablation included, and AS for patients with renal masses and a standard meta-analysis on survival outcomes was then conducted. Results The meta-analysis included seven studies containing 5809 patients. The results comparing NSI with AS were as follows: CSS (hazard ratio (HR) = 0.64, 95% confidence interval (CI): 0.46–0.89, P

A case report of a 02-month-old infant referred to us with incidental bilateral renal masses on ultrasound, which was reported as nephroblastoma/Wilms tumor on CT scan, no signs, and symptoms of infection. Urine and blood cultures were negative, which led to a percutaneous renal biopsy which showed Acute Lobar Nephronia. The infant was started intravenous antibiotics which resulted in the resolution of bilateral renal masses on serial ultrasounds.

Hemorrhage after robotic-assisted partial nephrectomy (RAPN) is uncommon but can cause significant morbidity. We present a case of acute hemorrhage isolated to the collecting system that was managed with renal artery embolization (RAE).A 76-year-old male developed sudden onset transfusion-dependent hematuria and hypotension following uncomplicated RAPN. He had no signs of intra-abdominal bleeding and his hypotension was responsive to volume resuscitation. Renal angiography identified a segmental artery with extravasation into the collecting system. RAE eliminated the patient's hematuria, the need for further transfusion, and allowed preservation of renal function. RAE is a viable option for collecting system hemorrhage following RAPN.

Renin secreting juxtaglomerular cell tumors are extremely rare benign tumors of the kidney. In this case, we highlight the atypical presentation of a young male patient presenting with vague complaints of worsening dyspnea, shortness of breath and anxiety. Initial workup of troponinemia and elevated BNP was initially most suggestive of a major cardiac event. An ejection fraction of 20% confirmed that this patient presented with heart failure. However, only further workup with imaging and renin and aldosterone labs revealed a functional renal mass as the cause. Timely intervention was pursued and pathology of the tumor was consistent with a juxtaglomerular cell tumor.

IgG4-related disease is a newly identified fibroinflammatory condition characterized by tumefactive lesions, a dense lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells and storiform fibrosis. Elevated serum IgG4 levels are frequently observed. IgG4-related disease affects predominantly middle-aged and elderly patients, with male predominance and responds favorably to steroids. The patients present with symptoms referable to the involvement of one or more sites either simultaneously or serially, usually in the form of mass lesions affecting various organs including pancreas, biliary tree, salivary glands, periorbital tissues, kidneys, lungs, retroperitoneum and lymph nodes. The case of a 61-year old male referred for therapy of a 6.6 cm tumorous lesion of the right kidney is presented. Histological assessment of the resected mass showed IgG4-rich sclerosing pseudotumor. The available literature is summarized, and diagnostic and therapeutic options for this condition are discussed. Consideration of a non-malignant disease may be reasonable even in cases of CAT scan findings suggestive of renal cancer.

Multiple, bilateral renal oncocytomas are uncommon, and the management of this condition is poorly described. Here, we report a case of multiple, bilateral, biopsy-proven renal oncocytomas that were successfully managed using percutaneous cryoablation. This procedure may serve as a less invasive treatment for patients with multiple, bilateral renal oncocytomas when compared to radical or partial nephrectomy.

Renal masses can be categorized as benign and malignant lesions. Among the renal malignancies, renal cell carcinoma is the most common malignancy. However, other rare malignant lesions should be considered in differential diagnosis. Primary renal lymphoma is quite rare and might be mistaken for renal cell carcinoma. Due to lack of lymphatic tissue in the kidney, pathogenesis of renal lymphoma is controversial. In the present case, a 75- year-old man presented with a locally advanced renal mass and after resection of the mass, a diagnosis of Non-Hodgkin’s lymphoma was confirmed.

Previous studies suggested that the apparent diffusion coefficient (ADC) value could help in the differentiation and characterization of the benign and malignant renal masses.However, there is still wide overlap in the ADC values between the benign and malignant tumors. Objectives: To retrospectively assess the usefulness of the diffusion weighted imaging (DWI) for the characterization and differentiation between benign and malignant renal masses. Methods: A total of 87 renal and/or upper ureteric masses were included in our study. The signal intensity of the lesions was assessed on both the DWI and ADC map and the ADC value was calculated. t test, ANOVA test and Receiver operating characteristic (ROC) curve analysis were performed. Results: The ADC values of benign lesions were significantly higher than those of the malignant masses [3.2 versus 1.3 × 10−3 mm2/s], Median, P

Non-Hodgkin’s lymphoma is a multisystem disease presenting with painless lymph node involvement in patients between 40 and 70 years of age. Kidney failure can be seen in about 10% of lymphoma patients due to different reasons. However, renal failure caused by lymphomatous parenchymal infiltration of the kidneys is very rare. In this study, we present a case of bilateral primary renal lymphoma presenting with acute renal failure.

Background and objectives: Cryoablation is emerging as a safe and effective therapeutic option for treating renal cell carcinoma. This study analyzed the safety and long-term oncological outcomes of cryoablation in our center. Materials and methods: Patients who underwent computed tomography (CT)-guided percutaneous cryoablation between February 2011 and June 2020 for one or more clinically localized renal tumors were identified. Technical success and treatment efficacy were assessed. Post-procedural complications were classified according to the Clavien-Dindo system. Recurrence–free survival was determined for biopsy-proven malignant renal tumors. Results: A total of 174 renal tumors, 78 of which were biopsy-proven malignant carcinomas, were treated in 138 patients (97 males and 41 females, mean age: 73 years, range: 43–89 years). Mean tumor size was 2.25 cm and 54.6% of the lesions required a complex approach. Technical success was achieved in 171 out of 174 tumors (98.3%). Primary treatment efficacy was 95.3% and increased to 98.2% when retreats were taken into account. The overall complication rate was 29.8%. No complications of Clavien-Dindo grade III or more were encountered. Median follow-up was 21.92 months (range: 0.02–99.87). Recurrence-free survival was 100% at 1 year, 95.3% (95% CI: 82.1%–98.8%) at 3 years, and 88.6% (95% CI: 71.8%–95.7%) at 5 years. Conclusions: Cryoablation is a safe and effective technique for the treatment of small renal lesions, with no major complications when performed by expert interventional radiologists. The multidisciplinary discussion is essential, especially considering the high number of histologically undetermined lesions. Our long-term oncological outcomes are encouraging and in line with the literature.

The detection of a renal mass is a relatively frequent occurrence in the daily practice of any Radiology Department. The diagnostic approaches depend on whether the lesion is cystic or solid. Cystic lesions can be managed using the Bosniak classification, while management of solid lesions depends on whether the lesion is well-defined or infiltrative. The approach to well-defined lesions focuses mainly on the differentiation between renal cancer and benign tumors such as angiomyolipoma (AML) and oncocytoma. Differential diagnosis of infiltrative lesions is wider, including primary and secondary malignancies and inflammatory disease, and knowledge of the patient history is essential. Radiologists may establish a possible differential diagnosis based on the imaging features of the renal masses and the clinical history. The aim of this review is to present the contribution of the different imaging techniques and image guided biopsies in the diagnostic management of cystic and solid renal lesions.

Primary leiomyosarcomas of the inferior vena cava (IVC) are rare tumors associated with poor prognosis, and surgical resection with the goal of obtaining negative margins is the gold standard for initial treatment. Tumor characteristics of both extraluminal extension into renal parenchyma and intraluminal extension of the subdiaphragmatic IVC are even less common. The prognosis of vascular leiomyosarcomas is determined by the location and the size of the tumor, as these factors determine the risk of local recurrence and metastasis. We present a case of a 30-year old female incidentally found to have a 14 cm right renal mass and IVC thrombus.

Primary squamous cell carcinoma (SCC) of the renal pelvis is exceedingly rare and is associated with advanced stage at diagnosis and a poor prognosis. Diagnosis is often difficult due to vague presenting symptoms and nonspecific radiologic findings. The mainstay of treatment is nephrectomy, with cisplatin based chemotherapy and palliative radiation reserved for metastatic disease. We report a SCC of the renal pelvis in a 72 year-old female who presented with abdominal pain. To date, this is the largest SCC originating from the renal pelvis reported in the literature, made even more exceptional by the lack of antecedent risk factors.